水稻粒重變異與產量及相關生理性狀間關係之研究

Abstract

為探討藉增加水稻平均粒重以提高產量的可行性，利用中粒型品種臺農67號，大粒型品種Pegonil及以臺農67號為輪迴親之回交第四與五代並經自交固定之植株為材料，調查產量性狀與乾物質生產能力，分析各器官全氮及非構造性碳水化物(TNC)濃度，以瞭解粒重變異與產量及相關生理性狀間的關係。試驗結果證明大粒型口種生產力受限於單位面積總粒數，密植栽培可提高單位面積乾物質與殼粒產量，其效果以第一期作較為明顯。所選用三個回交第四代系統之千粒重為28.5~32.2g，一穗穎花數、結實率、全株乾物重與殼粒產量均與臺農67號相近；選用八個回交第五代系統之千粒重介於25.3~34.7g，其他產量構成要素之變異亦大，但仍有部份系統之粒重較高，而且乾物質與稻殼產量與臺農67號表現相同，顯示回交系統之生產潛力優於大粒型品種。抽穗期葉片全氮濃度公大粒型品種顯著為高，成熟期則相近或較低，充實殼粒度亦以大粒型品種為，顯示有大量氮素轉移現象發生；回交第四代系統葉片氮濃度與大粒型品種相近，回交第五代系統之表現則與臺農67號相同，亦即品種與系統間之氮素代謝作用與利用效率具有差異。第一期作抽穗期莖稈TNC濃度於品種及回交系統間多無差異，成熟期之濃度則以回交系統較大粒品種為高，可能表示具有較優之光合成能回交系統間多無差異，念熟期之濃度則以回交系統較大粒品種為高，可能 表示具有較優之光合成能力；第二期作抽穗期之莖稈TNC濃度亦以大粒型品種最低，但成熟期則無顯著差別，應為環境因子之作用結果。本試驗所用回交材料雖然仍不能稱為臺農67號之大粒isogenic系統，但其部分農藝、生理與產量性狀已較大粒品種Pegonil有所改良，顯示經由增加粒重以提高產量之生理理論應屬可行。 A medium-grain variety, Taiung 67, a large-grain variety, Pegonil, and their BC-4 and BC-5 offsprings were used in this experiment to study the relationship between grain weight and yield performance in rice. Results indicated that grain yield of large-grain variety was limited by total spikelet number per unit area of land. Dense planting could increase both panicle and grain numbers per unit area and hence grain yield. The effect was more significant in the first crop season. Thousand-grain-weight to the three BC-4 offsprings (28.5-32.2 g) was significantly higher whereas panicle number per hill and spikelet number per panicle were similar as compared to those of Tainung 67 variety. Production of total dry matter and grain was also comparable to those of Tainung 67 variety. Production of total dry matter and grain was also comparable between BC-4 populations and Tainung 67. Thousand-grain-weight of the eight BC-5 offsprings was between 25.3 and 34.7 g. Pronounced variation was also observed on other yield components. However, a number of the BC-5 populations possessed higher grain weight with total dry matter and grain yield comparable to those of Tainung 67, indicating significant improvement in yield potential as compared to the large-grain variety Pegonil. Leaf N concentration of Pegonil variety potential as compared to the large-grain variety Pegonil. Leaf N concentration of Pegonil variety was higher at heading but lower at maturity stage than Tainung 67. Grain N concentration was also markedly higher for Pegonil. Those facts suggested significant redistribution of N during the grain-filling period. Leaf N concentration was similar between Pegonil and BC-4 and between Tainung 67 and BC-5 populations which indicated possible variations in N metabolism and utilization efficiency between plants of different grain weight. No difference in culm TNC concentration at heading stage existed between virilities and backcross offsprings in the first crop season. Culm TNC at maturity was higher for backcross plants than for Pegonil plants, presumably the result of higher photosynthetic capability and more balanced carbon budget for the former. Backcross populations used in this experiment was not isogenic in terms of their genetic homogeneity. However, their agronomic, physiological and yield characteritics had been improved significantly compared to the large-grain Pegonil. It was therefore concluded that physiologically, it should be possible to enhance grain yield of rice through increasing grain weight.